Pregnancy tests

• Pregnant woman secrete a hormone called HCG which is excreted in their urine. The test can detect the HCG.
• Testing strip

  • 2 important parts
  • On the right- monoclonal antibodies specific to HCG (bind to HCG hormone when in contact)
  • These antibodies are fixed to the strip and can't move
  • On the left- where you urinate. Contains blue beads covered in HCG specific antibodies, but these a free to moved around.
  • When not pregnant the urine will wash the antibodies past the strip and it won't go blue
  • When pregnant the HCG binds the blue beads
  • So it will bind to the fixed antibodies to (fixed in place) the whole strip goes blue.
• Most pregnancy tests in real life have a second line acting as a control.